Difference between chemical physics and physical chemistry

[shpongle]

What is the difference between physical chemistry and chemical physics?

 

[TeethWhitener]

Whether you're a physical chemist or a chemical physicist depends on which funding agency you're applying to.

People have tried to tease out the differences between these terms for decades, with no real agreement (because so much of each field necessarily overlaps with the other). For me personally, I think of chemical physics as physics research that happens to occur in chemical systems (so molecular and atomic spectroscopy, for example), whereas physical chemistry is the application of physical concepts to chemical reactions (for example, thermochemistry, photochemistry, etc.). But be advised that plenty of other distinctions exist (none of which I find particularly helpful, tbh).

 

[Ygggdrasil]

In the context of graduate programs, physical chemists tend to have undergraduate degrees from chemistry departments while chemical physicists tend to have undergraduate degrees from physics departments. The actual research they do is probably very similar, and the distinction may mainly be in their approach to the work (e.g. having the perspective of a chemist vs a physicist).

 

[dextercioby]

Sorry for this (perhaps off-topic) side-remark, but the difference between physical chemistry and chemical physics is much smaller than the difference between algebraic geometry and geometric algebra. :)

 

[Fra]

Another distinction is that of the core focus, applications or research direction.

I usually don't hang out in chemistry section, but memories come up as for me personally when i was younger in elementary school.

My real interest in science STARTED in chemistry in elementary school as i was intrigued to understand WHY chemical reactions took place, where equiblirium was and why and the concept of entropy, and what determined the RATE of reactions etc. I think the reason why this caught my attention is that chemistry can be very fun and spectacular experimentally. But as i kept studying physical chemistry, I soon answered my original questions and learned how to phrase new ones i noticed that the new questions was always drifting more and more to physics, as the laws of physics underpins chemistry. So it was only natural to abandon my original chemistry plans, suddently chemistry was just an "application". And I have always been motivated by my own questions to understand things. Paradoxally this journey continuted into and almost through physics as well, and my stance today is that even a lot of "physics" is an "application" in terms of the foundations of physical law an even deeper physical inference theory, this is where i stand today but i still see the red line tracing back all the way to physical chemistry. But somewhere in there i also made a detour into cell biology, for a few years and gained a lot of essential insights into the limits to reductionism. sometime that was missing in my orignal journey from chemistry to fundamental physics.

So for me all these things belong together but its more your own personal drive that determines where you end up. I tend to go wherever the good questions leads me and that journey is the fun part anyway. All natural sciences has enough in common to allow paths in any direction. Even biology fits well in here. In particlar the connection between complex systems (such as life) and the most fundamental parts of physical law are extremely interesting, and still hold unanswered questions to me personally.

/Fredrik

 

[TeethWhitener]

I usually don't hang out in chemistry section

COME TO THE DARK SIDE. WE HAVE BEER.

 

[Fra]

COME TO THE DARK SIDE. WE HAVE BEER.

It´s funny that you mention beer. Brewing my own beer was the random spark that started my dive into cell biology and biochemistry. I spotted a homebrewing kit in a store and thought "why not? I need to try this". That was like opening a can of worms, and i soon realized that except for the flavour chemistry of malt and hops, the interesting part of beer was all about the chemical processes occurring inside yeast cells. And in order to understand those, one need to understand the "context" of the chemistry, which means also modelling the whole regulatory system of a single cell organism including as well as the whole cellular culture. The interesting part is that in non-animate chemistry chemical reactions are simply regulated by various catalysts etc, but in biochemsitry these things are further regulated by the host cell and expression and transcription of genes, making it virtually impossiuble to apply the traditional reductionist approach as it becomes a chaotic dynamical system. so one needs a different modeling strategy, such as metabolic network, where one needs a model for the evolutionary goals of the host organism. Needless to say i was perceived by fellow brewers as and technical oddball that was more interested in making mathematical models for yeast and brewing processes than of the waste product (the beer). But after 3-4 years my questions that motivated this detour was answered, and i haven't brewed since. But the avatar picture in my profile are from iodine staining of glycogen in brewers yeast.

/Fredrik

 

[Ygggdrasil]

Another distinction is that of the core focus, applications or research direction.

I usually don't hang out in chemistry section, but memories come up as for me personally when i was younger in elementary school.

My real interest in science STARTED in chemistry in elementary school as i was intrigued to understand WHY chemical reactions took place, where equiblirium was and why and the concept of entropy, and what determined the RATE of reactions etc. I think the reason why this caught my attention is that chemistry can be very fun and spectacular experimentally. But as i kept studying physical chemistry, I soon answered my original questions and learned how to phrase new ones i noticed that the new questions was always drifting more and more to physics, as the laws of physics underpins chemistry. So it was only natural to abandon my original chemistry plans, suddently chemistry was just an "application". And I have always been motivated by my own questions to understand things. Paradoxally this journey continuted into and almost through physics as well, and my stance today is that even a lot of "physics" is an "application" in terms of the foundations of physical law an even deeper physical inference theory, this is where i stand today but i still see the red line tracing back all the way to physical chemistry. But somewhere in there i also made a detour into cell biology, for a few years and gained a lot of essential insights into the limits to reductionism. sometime that was missing in my orignal journey from chemistry to fundamental physics.

So for me all these things belong together but its more your own personal drive that determines where you end up. I tend to go wherever the good questions leads me and that journey is the fun part anyway. All natural sciences has enough in common to allow paths in any direction. Even biology fits well in here. In particlar the connection between complex systems (such as life) and the most fundamental parts of physical law are extremely interesting, and still hold unanswered questions to me personally.

/Fredrik

This experience fits my own pretty well. I started studying biochemistry as an undergraduate, interested in understanding life at the molecular level. However, throughout this process, I began to realize that understanding a lot of molecular biology at the fundamental level required a greater knowledge of the physics and chemistry underlying biomolecular processes. I ended up taking a lot of physical chemistry courses and eventually pursuing a graduate degree in biophysics (working in a lab that does biophysical chemistry). So, to me, biochemistry became the application of more fundamental knowledge in physical chemistry.

 

[HAYAO]

Well we have a good journal for comparing the topic. Journal of Physical Chemistry (A, B, C, and letters) and Journal of Chemical Physics. The former is published by ACS (American Chemical Society) and the latter is published by AIP (American Institute of Physics). When you look through these two journals, we see rather a recognizable distinction although they overlap a lot. J. Chem. Phys. started out as a response to J. Phys. Chem. at the time refusing to publish theoretical chemistry. BTW, I love both of these journals.

J. Phys. Chem. has to do with working on chemistry of physical chemistry while J. Chem. Phys. has to do more with physics of chemistry. In another words, chemical physics is essentially physics and physical chemistry is essentially chemistry. As such, these two area works on two different level of scientific hierarchy: physical chemistry are higher in hierarchy while chemical physics are lower.Many quantum theoretical foundation of the physical side of chemistry has been published in J. Chem. Phys. (but more in Physical Reviews by APS). For example, Dexter's theory of exchange energy transfer was published in J. Chem. Phys. which is widely important in chemistry (he actually also accounted for various other mechanism of energy transfer. I don't know why people only recognize this paper for exchange mechanism). J. Phys. Chem. has been rather more experimental and very "chemistry" in their approach.Although the distinction is very hard to make, I would say that chemical physics are more physically rigorous.